Complete the energy cycle linking the enthalpy change of solution and the lattice energy of potassium chloride, $\text{KCl}$, together with the relevant enthalpy changes of hydration. Label the diagram. State symbols should be used.
Use the data in Table 1.1 to calculate the enthalpy change of hydration of magnesium ions, $\text{Mg}^{2+}$. Show your working.
Explain why the lattice energy of $\text{MgCl}_2$ is more exothermic than that of $\text{KCl}$.
Define the following term: enthalpy change of atomisation.
Define the following term: first electron affinity.
Explain what is meant by entropy, $S$.
Potassium chloride is very soluble in water at $20^{\circ}\text{C}$. Explain the solubility of potassium chloride by reference to change in entropy, $\Delta S$.
Use the Gibbs equation and your answer to (e)(ii) to predict whether potassium chloride is more soluble in water at $20^{\circ}\text{C}$ or at $80^{\circ}\text{C}$. Explain your answer.